1. Field of the Invention
The present invention relates to an external light-shielding layer, a display filter including the external light-shielding layer, and a display apparatus including the display filter. More particularly, the present invention relates to an external light-shielding layer which can raise a contrast ratio in a bright room, enhance brightness, and increase a viewing angle, a display filter including the external light-shielding layer, and a display apparatus including the display filter.
2. Description of Related Art
As modern society becomes more information oriented, technology of parts and devices related to image displays is remarkably advancing, and these parts and devices are becoming widespread. Display apparatuses utilizing parts and devices related to image displays are becoming significantly widespread and used for television apparatuses, monitor apparatuses of personal computers, and the like. Also, display apparatuses are becoming both larger and thinner.
Plasma display panel (PDP) apparatuses are generally gaining popularity as next-generation display apparatuses to simultaneously satisfy a trend of becoming larger, and of becoming thinner, when compared with cathode-ray tubes (CRTs) representing existing display apparatuses. The PDP apparatuses display images using a gas discharge phenomenon, and exhibit superior display characteristics such as display resolution, brightness, contrast, an afterimage, a viewing angle, and the like. Also, since the PDP apparatuses are generally seen as having the most appropriate characteristics for future high-quality digital televisions due to thin luminous display apparatuses of which enlargement is simpler than any other display apparatus, the PDP apparatuses are gaining popularity as display apparatuses and are replacing CRTs.
The PDP apparatus generates a gas discharge between electrodes by a direct current (DC) voltage or an alternating current (AC) voltage which are supplied to the electrodes, so that ultraviolet light is generated. Then, a phosphor is exited by the ultraviolet light, thereby emitting light.
However, the PDP apparatus has a defect in that an amount of emitted electromagnetic waves and near infrared light with respect to a driving characteristic is great, surface reflectivity of the phosphor is great, and color purity due to orange light emitted from neon (Ne), helium (He), or xenon (Xe) used as a sealing gas is lower than the CRT.
Therefore, the electromagnetic waves and the near infrared light generated in the PDP apparatus may have harmful effects on human bodies, and cause sensitive equipment such as wireless telephones, remote controls, and the like, to malfunction. In order to use the PDP apparatus, it is required to prevent emission of the electromagnetic waves and the near infrared light emitted from the PDP apparatus from increasing to more than a predetermined level. PDP filters having functions such as a shielding function against the electromagnetic waves, a shielding function against the near infrared light, a surface anti-glare function, enhancement of color purity, and the like, are used for shielding against the electromagnetic waves and the near infrared light while simultaneously reducing reflected light, and enhancing color purity.
The PDP apparatus is made of a panel assembly including a discharge cell where a gas discharge phenomenon occurs, and a PDP filter shielding the electromagnetic waves and the near infrared light. Since the PDP filter is equipped in a front unit of the panel assembly, transparency is required to simultaneously emit light and perform shielding functions.
External light may enter the panel assembly passing through the PDP filter in a condition that an outer surface is bright, i.e. in a bright room condition with the PDP apparatus according to the conventional art. Accordingly, an overlapping between incident light generated in the discharge cell of the panel assembly, and the external light entered passing through the PDP filter from the outer . surface occurs. Accordingly, a contrast ratio decreases in the bright room condition, and therefore screen display capacity of the PDP apparatus is deteriorated.
Also, when a separate light absorption pattern absorbing the external light is used to increase the contrast ratio, a problem is generated where brightness of the PDP apparatus decreases and the viewing angle decreases.
Therefore, an external light-shielding layer which can raise a contrast ratio in a bright room, enhance brightness, and increase a viewing angle is needed.